Date and Time on the Internet: Timestamps
draft-ryzokuken-datetime-updated-00

Document Type Active Internet-Draft (individual)
Author Ujjwal Sharma 
Last updated 2021-02-21
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Calendaring Extensions Working Group                           U. Sharma
Internet-Draft                                              Igalia, S.L.
Obsoletes: 3339 (if approved)                           21 February 2021
Intended status: Standards Track                                        
Expires: 25 August 2021

               Date and Time on the Internet: Timestamps
                  draft-ryzokuken-datetime-updated-00

Abstract

   This document defines a date and time format for use in Internet
   protocols that is a profile of the ISO 8601 standard for
   representation of dates and times using the proleptic Gregorian
   calendar.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on 25 August 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Two Digit Years . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Local Time  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Coordinated Universal Time (UTC)  . . . . . . . . . . . .   5
     4.2.  Local Offsets . . . . . . . . . . . . . . . . . . . . . .   5
     4.3.  Unknown Local Offset Convention . . . . . . . . . . . . .   5
     4.4.  Unqualified Local Time  . . . . . . . . . . . . . . . . .   5
   5.  Date and Time format  . . . . . . . . . . . . . . . . . . . .   6
     5.1.  Ordering  . . . . . . . . . . . . . . . . . . . . . . . .   6
     5.2.  Human Readability . . . . . . . . . . . . . . . . . . . .   6
     5.3.  Rarely Used Options . . . . . . . . . . . . . . . . . . .   7
     5.4.  Redundant Information . . . . . . . . . . . . . . . . . .   7
     5.5.  Simplicity  . . . . . . . . . . . . . . . . . . . . . . .   7
     5.6.  Internet Date/Time Format . . . . . . . . . . . . . . . .   7
     5.7.  Restrictions  . . . . . . . . . . . . . . . . . . . . . .   8
     5.8.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  10
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   7.  Normative references  . . . . . . . . . . . . . . . . . . . .  11
   8.  Bibliography  . . . . . . . . . . . . . . . . . . . . . . . .  12
   Appendix A.  Day of the Week  . . . . . . . . . . . . . . . . . .  12
   Appendix B.  Leap Years . . . . . . . . . . . . . . . . . . . . .  13
   Appendix C.  Leap Seconds . . . . . . . . . . . . . . . . . . . .  13
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Date and time formats cause a lot of confusion and interoperability
   problems on the Internet.  This document addresses many of the
   problems encountered and makes recommendations to improve consistency
   and interoperability when representing and using date and time in
   Internet protocols.

   This document includes an Internet profile of the [ISO8601] standard
   for representation of dates and times using the proleptic Gregorian
   calendar.

   There are many ways in which date and time values might appear in
   Internet protocols: this document focuses on just one common usage,
   viz. timestamps for Internet protocol events.  This limited
   consideration has the following consequences:

   *  All dates and times are assumed to be in the "current era",
      somewhere between 0000AD and 9999AD.

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   *  All times expressed have a stated relationship (offset) to
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